FEEDING

Echinoderms are heterotrophs and have several methods of feeding. Some are carnivores while others are herbivores. Carnivores use their tube feet to pry open the shells of bivalve mollusks such as clams and scallops. Once the shell has been broken open, the starfish flips its somach out of its mouth, pours out enzymes, and digests its prey in the prey's own shell. After the sea stars haave finished eating, it removes its stomach from the shell and moves it back into his mouth. Sea stars usually eat snails, corals, and even other echinoderms. Some echinoderms are also herbivores, such as sea urchins, scrape algae from rocks by using their 5-part jaw. Sea lilies, basket stars, and some brittle stars, use tube feet on flexible arms to capture plankton that float by on ocean currents. This method of feeding is called filter feeding. The last method is the detritus feeders. The move as a large suction and pick up half sand and detritus. Later, they will digest organic materials and excrete the sand grains.